Thanks to shows like CSI, everyone's an forensic expert these days. 

At least they think they are. The reality, like anything, is far more practical, mundane and skilled than anything you're likely to see on TV. 

But if Prime's Forensics NZ is anything to go by, it's no less interesting or informative. 

It's not quite like it is on CSI in Kiwi crime labs.

So just what do forensics driven fictional shows leave out? Here's a list of 10 key tools in forensic science, compiled by ESR's forensic biology manager Sarah Cockerton: 

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ESR

ESR's forensic biology manager Sarah Cockerton

1. New Zealand has a DNA Databank

New Zealand was only the second country in the world to set up a national DNA Database for the collection of DNA profiles from individuals and DNA profiles from crime samples.  

ESR manages the DNA Databank on behalf of the NZ Police and since its introduction in 1996 there are now over 190 000 DNA profiles from individuals and over 40 000 DNA profiles from crime samples.  

The overall success rate for DNA Databank matching in NZ is world-leading with more than 70 per cent of the profiles from crime samples linking to the profile of an individual on the Databank and more than 30 per cent linking to another crime.

SPP

Environmental Science and Research forensic scientist, Dr Sally Coulson for TV show Forensics NZ.

2. Much of your DNA code is the same from person to person

DNA is the molecule found in virtually every cell of your body. It is inherited from your mother and father and carries genetic information from one generation to the next. Much of your DNA is the same from person to person, it is what gives you two eyes and two legs for example. However, there are regions on the DNA that are known to vary a great deal between people and these are the areas a forensic scientist is interested in.  

Forensic DNA analysis compares these areas of DNA obtained from a crime scene sample, to the same areas of DNA from an individual involved in the investigation.

The scientist will determine if that individual could or could not be the source of the DNA found at the scene.  If a correspondence is found, this evidence is then evaluated statistically to give a numerical value for the weight of the match.

3. The last time you washed your hands matters

DNA can be obtained from all sorts of different samples left behind at a crime scene.  Blood, clothing, partially eaten food, hair, chewing gum, cigarette butts and even earwax, to name a few.  

An individual can even leave their DNA on objects they have touched at a scene. The ability of a scientist to obtain a DNA profile from a touched item can depend on all sorts of factors such as the type of surface, the amount of contact, and the last time the individual washed their hands.

4. Every contact will leave a trace

Every contact will leave a trace and as such a scientist at a crime scene will be looking for everything and anything left behind.  

Bloodstains, fibres, paint, glass and shoeprints, are some examples of the evidence that may be collected. Some types of evidence are not always visible to the naked eye and the scene examination will include protection of areas where this evidence may be.  

Take shoeprints for example, some shoeprints in certain substances or on certain surfaces are not visible. Scientists use different techniques to enhance and visualise shoeprints dependant on the surface.

5. Blood spatter tells a story

Scientists examine bloodstains at scenes to help reconstruct the events that created them, this is called Bloodstain Pattern Analysis.  

The size, shape, distribution and location of the bloodstains can be used to determine where the blood came from, what type of wound was produced and how many blows were struck.  DNA testing can tell us who's blood it is and bloodstain pattern analysis can tell us how it got there.

6. Luminol lights the way

Tiny traces of diluted blood can remain at a scene even after the scene has been cleaned.  Scientists use a chemical called luminol that reacts with the smallest traces of diluted blood that may be present and produces a bluish green glow that is visible in the dark.  

Luminol solution is sprayed over the crime scene in darkness. Sometimes it is even necessary to ask Police to have street lights turned off. It is a very sensitive test which means it is very difficult to remove all traces of blood from an event.  Luminol can be used to show evidence of clean-up of blood, the original distribution of blood and even drag marks and footwear impressions in blood that can be followed for quite long distances.

This makes luminol testing very helpful in the reconstruction of the events at a crime scene.

7. Tears can tell a killer

Forensic scientists examine areas of damage on clothing to help provide information about the events that created the damage.  

The scientist may be asked questions such as whether an area of damage is from cutting or tearing, if the damage is recent, and what type of implement caused the damage.  

The overall condition of the garment, the characteristics of the fabric, and features of the damage including its size and shape, and the appearance of the individual fibres can be used to help answer these questions.    

8. Forensic scientists aren't know it alls

Forensic scientists have their own areas of expertise each requiring specialist knowledge and skills.  Below are a few of the various areas of expertise:

Scientists that carry out examinations at crime scenes are expert in evidence collection and reconstruction of the scene.  

DNA scientists can analyse and interpret DNA profiling results to see if an individual could or could not be the source of DNA left behind at a crime scene.  

Firearms and toolmark experts can examine a bullet to see if it came from a particular gun or an area of damage to see if it was produced by a particular tool.  

The comparison of paint fragments, glass and fibres from scenes to that collected from an individual requires specialist skills and knowledge.  

9. It's not like CSI

The examination of a crime scene can involve extremely long hours and hard physical work, sometimes in very difficult conditions.  

I once gave a lecture entitled "Filth, dirt and body fluids" to inform our laboratory based staff what it is really like at a crime scene.  Although the work can be tough it is also very rewarding. We get to work with experts in other forensic fields, such as Fingerprint experts and Pathologists, who just as passionate about their jobs as we are.  

No day is the same and the work is always varied.

10. It's Less CSI and more STRmixTM

ESR leads the world in resolving DNA mixtures.  A mixed DNA profile is one where there is DNA from more than one person in the crime scene sample.  

ESR, along with Forensic Science South Australia, developed a software programme that can resolve previously unresolvable mixed DNA profiles.  This means that more information can now be obtained from these crime scene samples.

The programme is called STRmixTM and laboratories around the world now use this software.

Forensics NZ  screens on Sundays at 8.30pm on Prime. 

 - Stuff